Hatcher Pass Avalanche Forecast

Issued: Sat, Apr 14, 2018 at 7AM

Expires: Sun, Apr 15, 2018

This is the last regular avalanche advisory for the season.

We will continue to post all OBSERVATIONS, so please keep contributing. Thank you all for a wonderful season. Enjoy the spring conditions!

Above 3,500ft Considerable

2,500 to 3,500ft Considerable

Below 2,500ft Considerable

Degrees of Avalanche Danger ?

1. Low
2. Moderate
3. Considerable
4. High
5. Extreme

Avalanche Danger Rose ?

Avalanche Problems ?

Problem Details

BOTTOM LINE

Avalanche danger will be LOW in the morning, RISING to CONSIDERABLE in the afternoon for Wet-Loose sluffs up to D2 in size, on E>W aspects, at all elevations, on slopes above 40º.  It will be likely to trigger a wet loose in the  afternoon and naturals will be possible. 

A LOW Hazard in the morning, RISING to MODERATE in the afternoon, exists for Wet-Slabs today up to D1.5-D2 in size, on SE>SW aspects, at all elevations. It will be possible to human trigger a wet-loose that sympathetically triggers a wet-slab, compounding both the hazard and risk of the avalanche problem. 

The avalanche problem is following the temperature trend. Higher temps=more avalanches, lower temps=fewer avalanches. 

 


WET LOOSE AVALANCHE PROBLEM

A LOW Avalanche Hazard rising to CONSIDERABLE in the afternoon, exists for Wet-Loose avalanches today. Expect wet-loose activity to be widespread on E>W aspects, at all elevations, on slopes above 40º,and stubborn in the morning, to touchy to trigger, in the afternoon. Expect sluffs to be D2 and moderate to large in size. Wet-sluffs will be unlikely in the morning, and likely to human trigger in the afternoon. Naturals will be possible in the afternoon as the solar and heat intensify.  

The tides have turned and spring has sprung. The intense heat and sun early this week have begun the transformation of the snowpack- especially on E>S>W aspects. Numerous wet-loose sluffs ran naturally this week, a few also responsible for triggering wet-slabs. The bed surface ranges from old crusts to weak facets on the ground.  A large wet avalanche was reported running within 100 yds of the Goldmint trail at 2 pm Friday.

The good news: this problem is totally predictable and avoidable; the bad news: if your timing is off, you’ll find yourself in the wrong place at the wrong time. Avoid steep east through west aspects, especially southerly, later in the day.  Enjoy sunny aspects in the morning or just as crusts are softening, or northerly aspects later in the day, as safer terrain choices. Temperatures are predicted to be a little cooler this weekend than the early part of the week which will assist in reducing the wet avalanche hazard.

A few things to keep in mind.  This is a good time to reassess route finding and up-routes. Just look around at HP and you’ll see many up-tracks now covered in wet debris. What you got away with a month ago, might not fly anymore. Much of the terrain at HP shares terrain features and run outs with sunny aspects on uproute or decent. Expect wet loose sluffs to run further than you might anticipate, especially if funneled in terrain traps. Wet avalanches may run slower, but still have destructive force.

Wet-loose , natural, S/SW , 3800′

 

 

 


WET-SLAB AVALANCHE PROBLEM

  A Low Avalanche Hazard in the morning RISING to MODERATE in the afternoon, exists for Wet-Slab avalanches today on SE>SW aspects, D1.5-D2 in size. Wet slabs will be unlikely in the morning, and possible to human trigger in the afternoon.

Warmer temperatures, rising to 50ºF at 3505′ on 4/13 and earlier in the week were responsible for natural wet slab activity. As the temperatures cool slightly this weekend, expect the wet avalanche hazard to decline, however, wet slab avalanches will still be possible to human trigger. Some wet slabs have been running to the ground and combined with other wet loose activity, add up to a considerable amount of debris.

WATCH TEMPERATURES OVER THE NEXT FEW WEEKS. Wet slabs are typically more challenging to predict. Last night’s freeze is a blessing in disguise. As soon as it ceases to freeze at night, expect to see large wet-slab avalanches. Combined with wet-loose- this problem has the potential to produce D2.5-D3 avalanches.

 

90 cm of 1F hardness slab over 40 cm of F hard , weak rounding depth hoar

 

 

Wet-loose that triggered a Wet-Slab, Idaho Peak, S/SE 4000′ during the intense warm up earlier in the week. Center of the photo is the sluff that sympathetically triggered the wet slab.  Many other natural wet loose sluffs are visible in this photo.

 

 


Looking forward:

Expect to see more wet loose and more wet slabs as the spring continues to transition to an isothermal snowpack. The lack of freezing temps at night will hasten the rate of wet slab activity.  The spring diurnal cycle will continue through the spring and avalanches may become larger as temperatures warm and the shed cycle progresses.

Pay attention to bullseye clues of instability to guide your route choices and stay safe this spring.


 

 

Recent Avalanche Activity

Numerous Wet-Loose Sluffs and and Wet-Loose that sympathetically triggered Wet-Slabs were observed or reported this week on E>W aspects at all elevations .

 

Marmot- Presidents, Wet-loose natural , S aspect

 

Microdot , human triggered wet-loose, SW aspect. Avy is in top center of photo and ran to the ground.

 

4/8 Human triggered wet-loose on S aspect (lookers right of slab) that triggered a dry slab on SW aspect as noted by the powder cloud in video, Stairstep Spines. This outlier avalanche shows our season long persistent slab problem that has been in dormancy and had not been a problem for weeks. Note all the debris choking the gully. Stay away from terrain traps like this one!

 

Wet loose, natural, lower Gold Chord, 3800′ E/SE aspect.

 

Cornices can not be trusted. Give cornices a wide birth and limit exposure underneath. Be more aware of cornice falls during times of significant warm up when they are more likely to fall, could crush you, or trigger an avalanche.

 

Recent Weather

This week’s weather at 3550′:

Temps averaged 34ºF, with a low of 28ºF and a high of a whopping 51ºF.

No new snow this week.

Overnight at 3550′:

Temps averaged 29° F.

No new snow overnight.

This week’s weather at 4500′:

Temps averaged 31ºF, with a low of 21ºF and a high of a 46ºF.

Winds averaged  SE 4 mph, max SE 17 mph . Gusts averaged SE 8 mph, max gusts SE 25 mph.

Overnight at 4500′:

Temps averaged  26ºF overnight.

Low winds overnight, with a max gust E 5 mph.


The diurnal heartbeat of a corn skiers paradise. Timing is everything.

 

 

 

 


NWS recreational forecast for Hatcher Pass here


NWS point forecast here


State Parks snow report here

 

 

Additional Info & Media

As long as we see freezing temps at night, expect the avalanche hazard to remain the same through the weekend.  The lack of freezing overnight temps, and rising daytime temps and sunshine, will drive the avalanche danger to RAPIDLY increase on E>W aspects for Wet Loose and Wet Slab avalanches.

 NWS is calling for temps 30º at 3000′.  Winds W 2-10 mph.

 

Posted in HPAC Forecasts.

Observations

Tell us what you're seeing out there.

Go to Hatcher Pass Observations